"heiner thiessen" <[EMAIL PROTECTED]> wrote To: "Sundials Mail List" <[email protected]> Sent: Saturday, February 14, 2004 8:52 AM Subject: solar clock
> Hi all, > I would like to set up an eastward turning globe with the help of an > anticlockwise 24 hour quartz movement so that the model > planet would turn once within the solar day. <snip> Why? I am truly baffled as to why you want to do this. The effect will be to make the same side of the globe face towards the sun at all times, rather as the same side of the moon always faces the earth. But I can't see why you would want to do this. Now, if you had a celestial globe, and you made it turn backwards once every sidereal day, I would see the point. So, could you please enlighten me. Thanks Chris Lusby Taylor 51.4N 1.3W The way to get a globe to mimic exactly the orientation of the earth, and thus to show, for instance, where the sun is shining, is to fix the globe rigidly with your location (51N, 1W) on top and north pointing north. The only 24 hour motor you need is the earth itself. Relative to the stars, the earth spins 366.25 times a year. If you spin the globe 'backwards' once every solar day, it will spin 366.25-365.25 times a year, so one turn every year. This will make the same line of longitude face towards the sun at all times -
